I have an 03 TJ with the I-6 motor. Noticed recently that system appeared to be losing coolant. I could find no visible leaks and so I took it to a local shop here for a pressure test. Mechanic says that he found a leak at the thermostat housing. He says he thinks he fixed it. I soon noticed the same coolant loss issue again. This time I got a UV additive and put it in the coolant. Upon checking with a black light, I could clearly see evidence of a leak from the bottom of the thermostat housing onto the top of the water pump. Having confirmed the leak I decided to replace the thermostat housing, gasket, thermostat and coolant sensor. On my first attempt to replace these items when I refilled the coolant it leaked from the housing like there was no gasket there at all. So I took it apart again and found that I had somehow cut the gasket which caused the leakage. After obtaining a new gasket (Fel-Pro) i installed the parts again but instead of refilling the whole system I just poured in enough coolant into the thermostat housing to fill it up to see if it would leak. There was no leak. So I refilled the coolant and ran the vehicle with the radiator cap off to check for thermostat functioning and to make sure no leaks appeared. The next morning I decided to drive the vehicle to work. I stopped at the Autozone to get another jug of coolant. When I came out I noticed a small puddle of green colored coolant underneath the radiator. I made a second stop and the same thing again. After work I went home and checked with the black light and again see evidence of a leak in the same area at the bottom of the thermostat housing. So it appears the leak is happening when the system is under pressure. I did not have a torque wrench when I installed the new housing so it may be possible that I did not apply sufficient torque. Any ideas would be appreciated. This is my first post to the forum. Thanks for any help.